This research investigates the role of estrogen in working memory and language comprehension in healthy elderly women (65-85 years old) and women who have been diagnosed with probably Alzheimer's Disease (AD). Recent research has shown an important link between estrogen and working memory and cognitive functioning within elderly normal and demented women, in that women receiving postmenopausal estrogen replacement therapy (ERT) have higher scores on certain cognitive and memory tests than do women without ERT. There has been only a limited investigation of whether ERT affects language functions, and most evidence has not supported a large role for ERT in language abilities, particularly in the healthy, non-demented women. However, most studies have not tested language abilities that are known to rely heavily on working memory capacity. A major hypothesis of the proposed research is that ERT does have a large effect working memory and on language comprehension processes that depend on working memory. New sensitive language and working memory measures developed by the PIs are predicted reveal this relationship. The research involves a novel combination of behavioral tests and functional magnetic resonance imaging (fMRI). Seventy-two women (36 normal elderly, 36 AD patients, half in each group currently receiving ERT) will be tested on an extensive battery of working memory tests and on language comprehension tests that are known to rely on working memory. All normal participants and some AD participants will receive fMRI scans while performing sensitive working memory tests. The combination of memory, language, and imaging data will illuminate the relationship between estrogen, working memory, language comprehension, and dementia.